The decision by Egyptian officials to virtually shut down Internet access to the country Friday marked an audacious escalation in the battle between authoritarian governments and tech-savvy protesters. It was also a direct challenge to the Obama administration's attempts to promote Internet freedom.

Internet access was cut off in Egypt shortly after midnight Friday, apparently after authorities ordered the country's five service providers to block it, according to experts. Cellphone service was also severely disrupted.

"The Egyptian government's actions ... have essentially wiped their country from the global map," James Cowie of Renesys, a New Hampshire-based company that monitors Internet data, said on the company's Web site.

The move came roughly a day after Secretary of State Hillary Rodham Clinton had publicly urged Egypt not to close off access to the technology and social media that were being used to organize demonstrations. On Friday, the administration denounced Egypt's action - first by using Twitter.

"Govt must respect the rights of Egyptian people & turn on social networking and internet," White House spokesman Robert Gibbs warned in a tweet.

U.S. officials concede that Twitter does not a revolution make. But they believe that such platforms have accelerated the pace of protest movements, citing the rapid coalescence of the Tunisian demonstrations that toppled that country's longtime leader, Zine el-Abidine Ben Ali, and the Egyptian demonstrations that erupted this week.

"From now on, any and all dissent movements will have technology as a core component," said Alec Ross, Clinton's senior adviser for innovation.

The Obama administration has elevated Internet freedom in U.S. diplomacy, and Clinton gave a major speech on the issue last year. The State Department is currently working on plans to spend $30 million on Internet freedom projects, including software that enables activists to break through firewalls imposed by oppressive governments.

The increased U.S. focus on Internet freedom, however, has gotten mixed reviews from bloggers and analysts.

Some warn that repressive governments will respond to the U.S. actions by intensifying their own technological assaults on bloggers and dissidents. Activists also worry that those receiving U.S. assistance could be tagged as Western puppets by oppressive governments.

"Having the U.S. and other Western governments as major actors in the Internet freedom field could present a real threat to activists who accept their support and funding," Sami Ben Gharbia, a prominent Tunisian Internet activist, wrote in an essay last fall.

Social media and hand-held communication devices are growing so quickly that U.S. officials are struggling to keep up with their political repercussions. In the past two years, the number of cellphones worldwide grew from about 4.1 billion to over 5 billion.